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md5 算法 说明 以及 c源代码

2008-02-28 15:52 417 查看
1、MD5算法是对输入的数据进行补位,使得如果数据位长度LEN对512求余的结果是448。即数据扩展至K*512+448位。即K*64+56个字节,K为整数。 具体补位操作:补一个1,然后补0至满足上述要求

2、补数据长度:
用一个64位的数字表示数据的原始长度B,把B用两个32位数表示。这时,数据就被填补成长度为512位的倍数。

3. 初始化MD5参数
四个32位整数 (A,B,C,D) 用来计算信息摘要,初始化使用的是十六进制表示的数字
A=0X01234567
B=0X89abcdef
C=0Xfedcba98
D=0X76543210

4、处理位操作函数
X,Y,Z为32位整数。
F(X,Y,Z) = X&Y|NOT(X)&Z
G(X,Y,Z) = X&Z|Y¬(Z)
H(X,Y,Z) = X xor Y xor Z
I(X,Y,Z) = Y xor (X|not(Z))

5、主要变换过程:
使用常数组T[1 ... 64], T[i]为32位整数用16进制表示,数据用16个32位的整数数组M[]表示。
具体过程如下:
/* 处理数据原文 */
For i = 0 to N/16-1 do
/*每一次,把数据原文存放在16个元素的数组X中. */
For j = 0 to 15 do
Set X[j] to M[i*16+j].
end /结束对J的循环
/* Save A as AA, B as BB, C as CC, and D as DD. */
AA = A
BB = B
CC = C
DD = D
/* 第1轮*/
/* 以 [abcd k s i]表示如下操作
a = b + ((a + F(b,c,d) + X[k] + T[i]) <<< s). */
/* Do the following 16 operations. */
[ABCD 0 7 1] [DABC 1 12 2] [CDAB 2 17 3] [BCDA 3 22 4]
[ABCD 4 7 5] [DABC 5 12 6] [CDAB 6 17 7] [BCDA 7 22 8]
[ABCD 8 7 9] [DABC 9 12 10] [CDAB 10 17 11] [BCDA 11 22 12]
[ABCD 12 7 13] [DABC 13 12 14] [CDAB 14 17 15] [BCDA 15 22 16]
/* 第2轮* */
/* 以 [abcd k s i]表示如下操作
a = b + ((a + G(b,c,d) + X[k] + T[i]) <<< s). */
/* Do the following 16 operations. */
[ABCD 1 5 17] [DABC 6 9 18] [CDAB 11 14 19] [BCDA 0 20 20]
[ABCD 5 5 21] [DABC 10 9 22] [CDAB 15 14 23] [BCDA 4 20 24]
[ABCD 9 5 25] [DABC 14 9 26] [CDAB 3 14 27] [BCDA 8 20 28]
[ABCD 13 5 29] [DABC 2 9 30] [CDAB 7 14 31] [BCDA 12 20 32]
/* 第3轮*/
/* 以 [abcd k s i]表示如下操作
a = b + ((a + H(b,c,d) + X[k] + T[i]) <<< s). */
/* Do the following 16 operations. */
[ABCD 5 4 33] [DABC 8 11 34] [CDAB 11 16 35] [BCDA 14 23 36]
[ABCD 1 4 37] [DABC 4 11 38] [CDAB 7 16 39] [BCDA 10 23 40]
[ABCD 13 4 41] [DABC 0 11 42] [CDAB 3 16 43] [BCDA 6 23 44]
[ABCD 9 4 45] [DABC 12 11 46] [CDAB 15 16 47] [BCDA 2 23 48]
/* 第4轮*/
/* 以 [abcd k s i]表示如下操作
a = b + ((a + I(b,c,d) + X[k] + T[i]) <<< s). */
/* Do the following 16 operations. */
[ABCD 0 6 49] [DABC 7 10 50] [CDAB 14 15 51] [BCDA 5 21 52]
[ABCD 12 6 53] [DABC 3 10 54] [CDAB 10 15 55] [BCDA 1 21 56]
[ABCD 8 6 57] [DABC 15 10 58] [CDAB 6 15 59] [BCDA 13 21 60]
[ABCD 4 6 61] [DABC 11 10 62] [CDAB 2 15 63] [BCDA 9 21 64]
/* 然后进行如下操作 */
A = A + AA
B = B + BB
C = C + CC
D = D + DD
end /* 结束对I的循环*/

源代码:


md5.h






#ifndef _RPCENG_MD5_H


#define _RPCENG_MD5_H




#include <string>




typedef struct




...{


unsigned int state[4];


unsigned int count[2];


unsigned char buffer[64];


} MD5Context;




void MD5_Init(MD5Context * context);




void MD5_Update(MD5Context * context, unsigned char * buf, int len);




void MD5_Final(MD5Context * context, unsigned char digest[16]);




bool MD5_File ( const char * filename,unsigned char *buff );




bool MD5_File ( const char * filename,std::string& md5str );




#endif /* end of _RPCENG_MD5_H */


















md5.cpp




#include <stdio.h>


#include <string.h>


#include "md5.h"




#define S11 7


#define S12 12


#define S13 17


#define S14 22


#define S21 5


#define S22 9


#define S23 14


#define S24 20


#define S31 4


#define S32 11


#define S33 16


#define S34 23


#define S41 6


#define S42 10


#define S43 15


#define S44 21




static unsigned char PADDING[64] =




...{


0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,


0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,


0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0


};




#define F(x, y, z) (((x) & (y)) | ((~x) & (z)))


#define G(x, y, z) (((x) & (z)) | ((y) & (~z)))


#define H(x, y, z) ((x) ^ (y) ^ (z))


#define I(x, y, z) ((y) ^ ((x) | (~z)))




#define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))

#define FF(a, b, c, d, x, s, ac) /
{ /
(a) += F((b), (c), (d)) + (x) + (unsigned int)(ac); /
(a) = ROTATE_LEFT((a), (s)); /
(a) += (b); /
}

#define GG(a, b, c, d, x, s, ac) /
{ /
(a) += G((b), (c), (d)) + (x) + (unsigned int)(ac); /
(a) = ROTATE_LEFT((a), (s)); /
(a) += (b); /
}

#define HH(a, b, c, d, x, s, ac) /
{ /
(a) += H((b), (c), (d)) + (x) + (unsigned int)(ac); /
(a) = ROTATE_LEFT((a), (s)); /
(a) += (b); /
}
#define II(a, b, c, d, x, s, ac) /
{ /
(a) += I((b), (c), (d)) + (x) + (unsigned int)(ac); /
(a) = ROTATE_LEFT((a), (s)); /
(a) += (b); /
}

static void MD5_Encode(unsigned char * output, unsigned int * input, int len)




...{


unsigned int i, j;


for (i = 0, j = 0; j < len; i++, j += 4)




...{


output[j] = (unsigned char) (input[i] & 0xff);


output[j + 1] = (unsigned char) ((input[i] >> 8) & 0xff);


output[j + 2] = (unsigned char) ((input[i] >> 16) & 0xff);


output[j + 3] = (unsigned char) ((input[i] >> 24) & 0xff);


}


}




static void MD5_Decode(unsigned int * output, unsigned char * input, int len)




...{


unsigned int i, j;


for (i = 0, j = 0; j < len; i++, j += 4)




...{


output[i] = ((unsigned int) input[j]) |


(((unsigned int) input[j + 1]) << 8) |


(((unsigned int) input[j + 2]) << 16) |


(((unsigned int) input[j + 3]) << 24);


}


}




static void MD5_Transform(unsigned int state[4], unsigned char block[64])




...{


unsigned int a = state[0], b = state[1], c = state[2], d = state[3], x[16];


MD5_Decode(x, block, 64);




/**//* Round 1 */




FF(a, b, c, d, x[0], S11, 0xd76aa478); /**//* 1 */




FF(d, a, b, c, x[1], S12, 0xe8c7b756); /**//* 2 */




FF(c, d, a, b, x[2], S13, 0x242070db); /**//* 3 */




FF(b, c, d, a, x[3], S14, 0xc1bdceee); /**//* 4 */




FF(a, b, c, d, x[4], S11, 0xf57c0faf); /**//* 5 */




FF(d, a, b, c, x[5], S12, 0x4787c62a); /**//* 6 */




FF(c, d, a, b, x[6], S13, 0xa8304613); /**//* 7 */




FF(b, c, d, a, x[7], S14, 0xfd469501); /**//* 8 */




FF(a, b, c, d, x[8], S11, 0x698098d8); /**//* 9 */




FF(d, a, b, c, x[9], S12, 0x8b44f7af); /**//* 10 */




FF(c, d, a, b, x[10], S13, 0xffff5bb1); /**//* 11 */




FF(b, c, d, a, x[11], S14, 0x895cd7be); /**//* 12 */




FF(a, b, c, d, x[12], S11, 0x6b901122); /**//* 13 */




FF(d, a, b, c, x[13], S12, 0xfd987193); /**//* 14 */




FF(c, d, a, b, x[14], S13, 0xa679438e); /**//* 15 */




FF(b, c, d, a, x[15], S14, 0x49b40821); /**//* 16 */






/**//* Round 2 */




GG(a, b, c, d, x[1], S21, 0xf61e2562); /**//* 17 */




GG(d, a, b, c, x[6], S22, 0xc040b340); /**//* 18 */




GG(c, d, a, b, x[11], S23, 0x265e5a51); /**//* 19 */




GG(b, c, d, a, x[0], S24, 0xe9b6c7aa); /**//* 20 */




GG(a, b, c, d, x[5], S21, 0xd62f105d); /**//* 21 */




GG(d, a, b, c, x[10], S22, 0x2441453); /**//* 22 */




GG(c, d, a, b, x[15], S23, 0xd8a1e681); /**//* 23 */




GG(b, c, d, a, x[4], S24, 0xe7d3fbc8); /**//* 24 */




GG(a, b, c, d, x[9], S21, 0x21e1cde6); /**//* 25 */




GG(d, a, b, c, x[14], S22, 0xc33707d6); /**//* 26 */




GG(c, d, a, b, x[3], S23, 0xf4d50d87); /**//* 27 */




GG(b, c, d, a, x[8], S24, 0x455a14ed); /**//* 28 */




GG(a, b, c, d, x[13], S21, 0xa9e3e905); /**//* 29 */




GG(d, a, b, c, x[2], S22, 0xfcefa3f8); /**//* 30 */




GG(c, d, a, b, x[7], S23, 0x676f02d9); /**//* 31 */




GG(b, c, d, a, x[12], S24, 0x8d2a4c8a); /**//* 32 */






/**//* Round 3 */






HH(a, b, c, d, x[5], S31, 0xfffa3942); /**//* 33 */




HH(d, a, b, c, x[8], S32, 0x8771f681); /**//* 34 */




HH(c, d, a, b, x[11], S33, 0x6d9d6122); /**//* 35 */




HH(b, c, d, a, x[14], S34, 0xfde5380c); /**//* 36 */




HH(a, b, c, d, x[1], S31, 0xa4beea44); /**//* 37 */




HH(d, a, b, c, x[4], S32, 0x4bdecfa9); /**//* 38 */




HH(c, d, a, b, x[7], S33, 0xf6bb4b60); /**//* 39 */




HH(b, c, d, a, x[10], S34, 0xbebfbc70); /**//* 40 */




HH(a, b, c, d, x[13], S31, 0x289b7ec6); /**//* 41 */




HH(d, a, b, c, x[0], S32, 0xeaa127fa); /**//* 42 */




HH(c, d, a, b, x[3], S33, 0xd4ef3085); /**//* 43 */




HH(b, c, d, a, x[6], S34, 0x4881d05); /**//* 44 */




HH(a, b, c, d, x[9], S31, 0xd9d4d039); /**//* 45 */




HH(d, a, b, c, x[12], S32, 0xe6db99e5); /**//* 46 */




HH(c, d, a, b, x[15], S33, 0x1fa27cf8); /**//* 47 */




HH(b, c, d, a, x[2], S34, 0xc4ac5665); /**//* 48 */






/**//* Round 4 */




II(a, b, c, d, x[0], S41, 0xf4292244); /**//* 49 */




II(d, a, b, c, x[7], S42, 0x432aff97); /**//* 50 */




II(c, d, a, b, x[14], S43, 0xab9423a7); /**//* 51 */




II(b, c, d, a, x[5], S44, 0xfc93a039); /**//* 52 */




II(a, b, c, d, x[12], S41, 0x655b59c3); /**//* 53 */




II(d, a, b, c, x[3], S42, 0x8f0ccc92); /**//* 54 */




II(c, d, a, b, x[10], S43, 0xffeff47d); /**//* 55 */




II(b, c, d, a, x[1], S44, 0x85845dd1); /**//* 56 */




II(a, b, c, d, x[8], S41, 0x6fa87e4f); /**//* 57 */




II(d, a, b, c, x[15], S42, 0xfe2ce6e0); /**//* 58 */




II(c, d, a, b, x[6], S43, 0xa3014314); /**//* 59 */




II(b, c, d, a, x[13], S44, 0x4e0811a1); /**//* 60 */




II(a, b, c, d, x[4], S41, 0xf7537e82); /**//* 61 */




II(d, a, b, c, x[11], S42, 0xbd3af235); /**//* 62 */




II(c, d, a, b, x[2], S43, 0x2ad7d2bb); /**//* 63 */




II(b, c, d, a, x[9], S44, 0xeb86d391); /**//* 64 */




state[0] += a;


state[1] += b;


state[2] += c;


state[3] += d;




memset((char *) x, 0, sizeof(x));


}




void MD5_Init(MD5Context * context)




...{


context->count[0] = context->count[1] = 0;




context->state[0] = 0x67452301;


context->state[1] = 0xefcdab89;


context->state[2] = 0x98badcfe;


context->state[3] = 0x10325476;


}




void MD5_Update(MD5Context * context, unsigned char * buf, int len)




...{


unsigned int i, index, partLen;


index = (unsigned int) ((context->count[0] >> 3) & 0x3F);


if ((context->count[0] += ((unsigned int) len << 3)) < ((unsigned int) len << 3))


context->count[1]++;


context->count[1] += ((unsigned int) len >> 29);




partLen = 64 - index;




if (len >= partLen)




...{


memcpy((char *) &context->buffer[index], (char *) buf, partLen);


MD5_Transform(context->state, context->buffer);




for (i = partLen; i + 63 < len; i += 64)


MD5_Transform(context->state, &buf[i]);


index = 0;


}


else




...{


i = 0;


}


memcpy((char *) &context->buffer[index], (char *) &buf[i], len - i);


}




void MD5_Final(MD5Context * context, unsigned char digest[16])




...{


unsigned char bits[8];


unsigned int index, padLen;


MD5_Encode(bits, context->count, 8);


index = (unsigned int) ((context->count[0] >> 3) & 0x3f);


padLen = (index < 56) ? (56 - index) : (120 - index);


MD5_Update(context, PADDING, padLen);


MD5_Update(context, bits, 8);


MD5_Encode(digest, context->state, 16);


memset((char *) context, 0, sizeof(*context));


}




// 计算文件的 MD5


// filename 文件名, 计算的 MD5 放入缓冲区 buff 中


// buff 长度为16 字节


bool MD5_File ( const char * filename,unsigned char *buff )




...{


FILE *file;


MD5Context context;


// unsigned char buff[16];


int i,len;


unsigned char buffer[0x0400];




if (!(file = fopen (filename, "rb")))




...{


printf ("%s can't be opened ", filename);


return false;


}


else




...{


MD5_Init (&context);


while (len = fread (buffer, 1, 1024, file))


MD5_Update (&context, buffer, len);


MD5_Final(&context,buff);


fclose (file);


for(i=0;i<16;i++)




...{


printf("%x",(buff[i] & 0xF0)>>4);


printf("%x",buff[i] & 0x0F);


}


printf(" ");


return true;


}


}




bool MD5_File ( const char * filename,std::string& md5str )




...{


FILE *file;


MD5Context context;


unsigned char buff[16];


int i,len;


unsigned char buffer[0x0400];






char md5char[16]=...{'0','1','2','3','4','5','6','7','8','9','a','b','c','d','e','f'};




if (!(file = fopen (filename, "rb")))




...{


printf ("%s can't be opened ", filename);


return false;


}


else




...{


MD5_Init (&context);


while (len = fread (buffer, 1, 1024, file))


MD5_Update (&context, buffer, len);


MD5_Final(&context,buff);


fclose (file);


for(i=0;i<16;i++)




...{


md5str += md5char[(buff[i] & 0xF0)>>4];


md5str += md5char[buff[i] & 0x0F];


}


return true;


}


}







测试:




int i =0,j,len,startTime,endTime;




MD5Context context;




unsigned char buff[16];






char str[7][100] =




...{




"",




"a",




"abc",




"message digest",




"abcdefghijklmnopqrstuvwxyz",




"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789",




"12345678901234567890123456789012345678901234567890123456789012345678901234567890"




};




for(i=0;i<6;i++)






...{




len = strlen(str[i]);




MD5_Init(&context);




MD5_Update(&context,(unsigned char *)str[i], len);




MD5_Final(&context,buff);




printf("MD5("%s") = ",str[i]);




for(j=0;j<16;j++)






...{




printf("%x",(buff[j] & 0xF0)>>4);




printf("%x",buff[j] & 0x0F);




}




printf(" *********************************************************** ");




}




printf("Wating... ");


std::string md5str;


MD5_File("tiger_c.jpg",md5str );


std::cout<<"::::::::::::::"<<md5str<<" ";


return 0;

MD5("") =
d41d8cd98f00b204e9800998ecf8427e
***********************************************************
MD5("a") =
0cc175b9c0f1b6a831c399e269772661
***********************************************************
MD5("abc") =
900150983cd24fb0d6963f7d28e17f72
***********************************************************
MD5("message digest") =
f96b697d7cb7938d525a2f31aaf161d0
***********************************************************
MD5("abcdefghijklmnopqrstuvwxyz") =
c3fcd3d76192e4007dfb496cca67e13b
***********************************************************
MD5("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789") =
d174ab98d277d9f5a5611c2c9f419d9f
***********************************************************
Wating...
::::::::::::::41fd801b9ae124d8b69de40c0961c615
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